UNIVERSITY   OF  CALIFORNIA   PUBLICATIONS 

IN 

AGRICULTURAL    SCIENCES 

Vol.  1 ,  No.  11 ,  pp.  34  1  -394,  plates  5- 1 5  January  31,  1917 


[NFLUENCE    OF    THE    COMPOSITION    AND 

CONCENTRATION  OF  THE  NUTRIENT 

SOLUTION  ON  PLANTS  GROWN 

IN  SAND  CULTURES 

BY 

ARTHUR  HUGO  AYRES 


INTRODUCTION 

Since  the  recognition  of  the  fact  that  the  mineral  content  of 
the  plant  body  is  derived  from  the  mineral  constituents  of  the  soil, 
the  part  which  the  soil  solution  takes  in  the  nutrition  of  the  plant 
has  been  the  subject  of  numerous  investigations  by  chemists,  plant 
physiologists,  and  soil  scientists,  who  have  made  large  contri- 
butions to  our  knowledge  in  this  important  field.  The  early 
investigations  of  Knop  and  other  plant  physiologists  showed 
conclusively  that  the  elements  which  are  essential  to  plant  growth 
are  carbon,  hydrogen,  oxygen,  nitrogen,  sulphur,  phosphorus, 
potassium,  magnesium,  calcium,  and  iron.  As  most  of  this  work 
was  done  before  the  development  of  the  new  chemical  and  physi- 
cal theories,  in  regard  to  solutions  in  particular,  the  problems 
dealing  with  the  absorption  of  these  elements  remain  for  expla- 
nation in  the  light  of  this  new  knowledge.  The  modern  period 
of  research  in  this  field  has  thus  been  characterized  by  an  in- 
tensive study  of  the  absorption  of  nutrient  elements  by  the  plant. 
The  earlier  conceptions,  which  had  a  marked  tendency  to  link 
each  element  with  some  specific  physiological  process  or  with  the 
development  of  some  morphological  part  of  the  plant,  have  been 


342        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

largely  discarded  in  view  of  the  recent  investigations,  which 
have  shown  that  plant  growth  is  not  a  simple  function  of  any 
any  particular  element,  but  is  to  a  very  large  extent  influenced 
by  the  combinations  of  elements  in  the  solution  from  which 
the  plant  derives  its  nourishment.  Thus  while  calcium  may 
in  certain  cases  act  as  a  neutralizer  of  oxalic  acid,1  it  exhibits 
a  more  general  function  of  antagonism  for  salts  of  potassium, 
sodium,  magnesium,  and  other  salts  which  would  be  toxic  if 
calcium  were  not  present.2  While  this  antagonistic  function 
may  be  characteristic,  it  would  seem  from  the  experiments  of 
Tottingham3  that  either  this  antagonistic  action  of  calcium  or 
the  toxic  effects  of  magnesium  are  influenced  by  the  total  con- 
centration of  the  solution.  Tottingham,  therefore,  concludes  that 
the  injurious  effects  of  magnesium  depend  not  only  on  the  amount 
of  calcium  present  but  also  upon  the  complex  balance  between 
all  the  salts  in  the  solution.  It  follows  that  while  the  later  in- 
vestigations have  undoubtedly  given  a  wider  conception  of  the 
role  of  the  various  nutrient  elements,  the  exact  relation  which 
exists  between  the  recognized  nutrient  function  of  these  elements 
and  the  balancing  function  in  the  solution  is  not  definitely  known. 
The  part  which  the  total  concentration  of  the  solution  takes 
in  the  complicated  problem  of  plant  nutrition  is  by  no  means 
clear.  On  the  one  hand,  the  experimental  evidence  of  Cameron4 
and  his  co-workers  shows  that  the  plant  growing  in  water  culture 
is  not  influenced  to  any  extent  by  wide  variations  in  the  total 
concentration  of  the  solution,  a  view  which  is  further  supported 
by  the  researches  of  Tottingham,5  who  concludes  that  nutrient 
solutions  ranging  from  0.01  per  cent  to  0.14  per  cent  do  not  affect 
the  dry  weight  in  the  case  of  wheat  grown  in  these  solutions. 
A  similar  view  is  taken  by  Stiles,"  who  thinks  that  the  individual 
variation  of  plants  grown  in  water  cultures  is  as  large  or  larger 
than  that  which  is  often  accredited  to  a  variation  in  the  compo- 


i  Schimper,  Flora,  vol.  73,  pp.  207-261,  1890. 

2  Loew,  Flora,  vol.  75,  pp.  368-394,  1892;  and  U.  S.  Dept.  Agric.  Bur. 
Plant  Ind.  Bull.  45,  1903;  Osterhout,  Bot.  Gaz.,  vol.  42,  pp.  127-134,  1906, 
and  vol.  44,  pp.  259-272,  1907. 

s  Tottingham,  Physiol.  Res.,  vol.  1,  pp.  133-245,  1914. 

*  Cameron,  Jour.  Phys.  Chem.,  vol.  14,  p.  320,  1910. 

s  Loc.  cit. 

o  Stiles,  Ann.  Bot.,  vol.  29,  pp.  89-96,  1915. 


1!H7|      Ayres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         343 

sition  of  the  solution.     In  decided  contrasl  to  1 1 1 « -  evidence  cited 

above,  we  have  the  investigations  of  Hall,  Brenchley,  and  Under- 
wood,7 who  eonelnde,  on  the  basis  of  their  results  with  barley 
plants  grown  in  a  standard  solution  of  four  different  concen- 
trations, thai  "the  growth  made  by  plants  in  the  soil  solution  is 
in  the  main  determined  by  the  amount  of  plant  food  they  con- 
tain," and  that  "the  concentration  of  the  nutrient  solution 
within  certain  wide  limits,  irrespective  of  the  total  amount  of 
the  plant  food  available,  is  a  factor  in  the  rate  of  plant  growth 
which  varies  directly  though  not  proportionally  with  the  strength 
of  the  solution  in  the  particular  mitrienl  or  nutrients  limiting 
the  growth.**  The  experiments  of  Shive8  are  of  considerable 
interest  in  this  connection.  "Wheat  was  grown  in  solutions  of 
three  different  total  concentrations,  0.1,  1.75,  and  4.00  atmos- 
pheres,  in  terms  of  possible  osmotic  pressure.  The  solution  used 
was  the  three-salt  solution  first  used  by  Birner  and  Lucanus9 
►  containing  Ca(NO.,)2,  MgS04,  and  KrLP04.     All  possible  sets 

of  proportion  of  these  salts  were  included  for  increments  of 
change  equal  to  one-tenth  of  the  total  possible  osmotic  pressure. 
As  judged  from  the  extensive  quantitative  data  collected,  Shive 
concludes  that  the  growth  of  wheat  plants  in  solutions  of  any 
given  salt  proportion  is  determined  by  the  concentration  of  the 
medium. 

In  the  course  of  some  experimental  work  concerning  the  drop- 
ping of  flowers  by  b\  species-hybrids  of  Nicotiana1"  it  seemed 
desirable  to  grow  a  considerable  number  of  plants  in  sand  cul- 
tures which  would  vary  widely  both  as  to  the  principal  nutrient 
I  elements,  nitrogen,  phosphorus,   and  potassium,   and   as  to  the 

total  concentration  of  all  of  the  nutrient  salts.  The  marked 
influence  of  the  nutrient  factors  upon  the  growth  of  the  plaid 
has  afforded  an  excellent  opportunity  for  a  somewhat  detailed 
study  of  the  influence  of  the  composition  and  concentration  .of 
the  nutrient  solution  upon  the  growth  of  one  of  the  higher  seed- 
plants  of  herbaceous  character. 


~  Hall,  Brenchley,   Underwood,   Jour.   Agric.   Sei.,   vol.   6,   pp.   278-301, 
1914. 

s  Shive,  Physiol.  Res.,  vol.  1,  pp.  327-396,  1915. 

9  Birner  and  Lucanus,  Landw.  Versuchsstat.,  vol.  8,  pp.   1  US— 1  77,   1886. 

10  Goodspeed  and  Ayres,  Univ.  Calif.  Publ.  Bot.,  vol.  5,  no.  9,  1916. 


344        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

The  Use  of  Sand  as  a  Culture  Medium 

The  ease  with  which  solutions  can  be  prepared  and  subse- 
quently analyzed  has  made  the  water-culture  method  especially 
desirable  in  investigations  of  the  role  of  nutrient  substances  in 
plant  growth.  A  solution  has  generally  been  recognized,  how- 
ever, to  be  otherwise  undesirable  as  a  medium  for  the  growth  of 
the  higher  plants,  since  the  root  system  is  kept,  during  the  course 
of  the  experiment,  in  an  unnatural  environment.  Thus,  while 
this  method  serves  admirably  for  analytical  purposes,  it  seems 
probable  that  the  plant  thus  subjected  to  an  unnatural  environ- 
ment will  suffer  certain  more  or  less  serious  physiological  dis- 
turbances. In  this  connection,  it  is  a  well-established  fact  that 
the  development  of  root  hairs  is  much  greater  in  sand  than  in 
water,11  the  resistance  of  the  substratum  favoring  root-hair  pro- 
duction.12 Roots  in  general  grow  longer  and  thinner  in  water 
than  in  sand  or  moist  soil.  Hall,  Brenchley,  and  Underwood13 
think  that  the  more  vigorous  growth  of  barley  in  sand,  as  com- 
pared with  water  cultures,  is  due  to  more  efficient  aeration  of  the 
former.  It  would  seem,  therefore,  that  sand  is  preferable  to 
water  as  a  culture  medium,  since  in  sand  cultures  the  physical 
conditions  present  about  the  root  system  more  nearly  simulate 
those  found  in  the  soil.  It  is  still  a  question  just  what  part  these 
physical  conditions  may  have  in  plant  nutrition.  Undoubtedly 
such  physical  reactions  as  capillarity14  and  adsorption18  must  be 
important  factors,  since  both  the  absorption  and  availability  of 
nutrient  salts  would  be  affected  by  these  physical  phenomena. 
Breazeale1"  has  shown  that  the  effect  of  concentration  in  sand 
cultures  is  very  different  from  that  in  water  cultures,  the  best 
concentration  for  wheat  in  water  being  three  hundred  parts  per 
million,  while  in  sand  it  is  in  the  vicinity  of  two  thousand  five 
hundred  parts  per  million,  an  effect  which  is  no  doubt  largely  due 
to  the  adsorption  of  certain  salts  or  ions  by  the  sand  particles. 


11  Sehwarz,  Bot.  Inst.  Tubingen,  vol.  1,  pp.  135-188,  1883. 

1=  Snow,  Bot.  Gaz.,  vol.  40,  pp.  12-43,  1905. 

is  Loc.  cit. 

i*  Bell  and  Cameron,  Jour.  Phys.  Chem.,  vol.  10,  p.  659,  1906. 

is  Sehreiner  and  Failyer,  U.  S.  Dept.  Agrie.  Bull.  32,  1906. 

i'1  Breazeale,  Science,  n.  s.,  vol.  22,  pp.  146-149,  1905. 


L917]       lyres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         345 

The  physical  effects  of  sand  as  a  medium  for  planl  growth  have 
been  shown  recently  in  a  striking  manner  by  McCall,11  who  added 

to  saml  tin-  solutions  which  Shive18  used  as  water  cultures,  with 
the  resull  thai  much  larger  quantities  of  the  nutrient  salts  were 
required  than  when  the  same  species  of  plant  was  grown  in  water 
culture.  The  sand-culture  method  was  selected  for  the  present 
work  with  the  above  evidence  in  mind,  and  also  because  the 
growing  period  of  the  tobacco  plant  is  long  and  1  his  method 
precluded  the  tedious  changing  of  solutions  necessary  when  the 
water-culture  method  was  used. 

Experimental  Material 

The  planl  which  was  used  in  the  present  series  of  investiga- 
tions was  a  tobacco  of  hybrid  origin  derived  from  a  cross  between 
Nicotiana  sylvestris  (U.  C.  B.  G.  69/09)  and  Nicotiana  tabacum 
var.  macrophylla  (U.  C.  B.  G.  22/07)  and  known  in  the  Tni- 
versity  of  California  Botanical  Garden  as  U.  C.  B.  G.  H38.1S 
The  plants  to  be  used  were  raised  from  seed  and  were  transferred 
as  seedlings  to  the  sand  from  the  flats  in  which  they  were  grown 
after  carefully  washing  the  roots  free  from  adhering  soil  par- 
ticles. In  picking  out  seedlings  from  the  flats  care  was  taken  to 
choose  from  the  large  numher  of  plants  available  only  those 
which  were  most  nearly  uniform  with  reference  to  size  and 
general  appearance.  The  plants  were  kept  during  the  experiment 
in  a  well-ventilated  greenhouse. 

The  sand  used  was  a  light-colored  beach  sand  which  on 
analysis  by  means  of  the  acid-digestion  method  of  Hilgard  showed 
the  following  composition: 

Fe,0;     0.592  per  cenl  P.,0,       0.004  per  cenl 

U,0,      0.46  pen-out  MgO      0.28  per  cenl 

K,<>        Trace  CaO        0.06  per  cent 

The  water-holding  capacity  was  22  per  cent  when  saturated. 
The  sand  was  prepared  for  the  experiment  by  washing  in  a 
heavy  stream  of  tap  water  which  was  allowed  to  percolate  through 


17  Unpublished  work. 

i^  Loc.  cit. 

i»Setchell,  Univ.  Calif.  Publ.  Bot.,  vol.  5,  pp.  1   B6,  1912. 


346        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

a  column  of  the  sand  for  a  period  of  twenty-four  hours.  The 
excess  of  tap  water  retained  by  the  sand  was  in  turn  washed  out 
with  distilled  water.  While  this  sand  is  inferior  to  the  best 
grade  of  pure  quartz  sand  in  freedom  from  inorganic  material, 
it  is  unable  to  supply  available  nutrient  elements  in  sufficient 
quantity  to  cause  any  perceptible  increase  in  growth  (pi.  14). 
Two  thousand  gram  portions  of  the  sand  treated  as  above  were 
weighed  into  six-inch  flower-pots  winch  had  been  previously 
prepared  by  dipping  them  into  melted  paraffin.  The  paraffining 
effectually  closed  the  pores  and  prevented  the  absorption  of  the 
culture  solution  by  the  pot. 

Distribution  op  Nutrient  Salts 

The  pots  were  divided  into  three  different  groups  designated 
as  series  I,  II,  and  III,  each  series  consisting  of  twenty  pots 
divided  into  groups  of  five  pots  each,  and  a  duplicate  in  each 
case,  making  forty  pots  in  all  in  each  series.  In  series  I,  nitrogen, 
as  NaN03,  was  the  varying  factor  within  each  group,  the  weight 
of  each  of  the  other  salts  being  held  constant.  Thus,  in  series  I, 
the  pots  1  to  .5  in  each  of  the  four  groups  contained  NaN03  as 
follows:  0.02,  0.2,  1.0,  2.0,  3.0  grams.  In  a  similar  manner  phos- 
phorus and  calcium,  as  Ca(H2P04)2,  were  varying  factors  in 
series  II,  while  in  series  III  potassium,  as  K2S04,  was  varied.  As 
noted  above,  the  twenty  plants  of  each  series  were  divided  into 
four  groups  designated  respectively  as  A,  B,  C,  and  D,  each  group 
consisting  of  five  plants  and  a  control  for  each.  The  weight  of 
one  varying  factor  remained  the  same  in  pots  of  like  number 
through  all  four  groups.  Thus  plants  I  A  1,  I  B  1,  I  C  1,  and 
I  D  1  each  contained  0.02  grams  of  NaNO,,  and  I  A  2, 1  B  2,  I  C  2, 
and  I  D  2  contained  0.2  grams  of  NaNO:..  But  from  group  A 
to  D  the  weight  of  the  other  nutrient  factors  decreases,  so  that 
group  D  contains  two-thirds,  C  one-half,  and  D  one-fourth  the 
weight  of  each  of  these  nutrient  factors  as  present  in  the  A  group. 
The  effect  of  this  distribution  of  salts  is  to  give  at  least  three 
important  variables.  First,  the  single  nurient  salt  in  increasing 
proportions  from  plant  1  to  plant  5  in  each  group,  and  second, 
the  factor  of  total  concentration  which  decreases  from  group  A 


l!U7|      Ay  res:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         34' 

to  group  D  in  each  scries.  The  third  important  variant,  the 
balance  of  sails  in  the  solution,  follows  as  a  matter  of  necessity, 
since  the  single  nutrient  salt  added  in  increasing  quantities  from 
plant  1  to  plant  5  is  added  with  uniform  variation  and  in  the  same 
quantity  in  each  group,  while  the  quantities  of  the  other  salts, 
although   constant    within   a   group,  are   not    constant    within   all 


TABLE  1 

w  i  ii.mt  in  Grams  of  Salts  Added  to  Each  Pot  Containing  2000  Grams 

of  Sand 

(In  the  following  table  the  reman  numerals  indicate  the  series  numbers, 
ami  the  letters  are  those  of  the  corresponding  groups.) 


o 

O 

« 

d 

DO 

= 

W 

o* 

CO 

.  s 

6 
x 

- 

0  = 

z? 

d 
3& 

d  = 
w  5 
«fG 

-  v. 

c  £ 
x  - 

o  c 

«  3 

6 

c 

dl 
y.  r- 

d 

-  cc 

da 

C     - 
C  C 

e2- 

IA1 

.02 

1.2 

2.4 

.96 

1.5s 

11C1 

1.5 

.02 

1.2 

.48 

3.20 

IA2 

.2 

1.2 

2.4 

.96 

4.76 

IIC2 

1.5 

.10 

1.2 

.48 

3.28 

[A3 

1.0 

1.2 

2.4 

.96 

5.56 

IK':: 

1.5 

.20 

1.2 

.48 

3.38 

IA4 

2.0 

1.2 

2.4 

.96 

6.56 

1IC4 

1.5 

1.0 

1.2 

.48 

Lis 

EA5 

3.0 

1.2 

2.4 

.96 

7.56 

IIC5 

1.5 

2.0 

1.2 

.48 

5.18 

IB1 

.02 

.8 

1.6 

.64 

3.06 

IID1 

.75 

.02 

.6 

.24 

1.61 

1  B2 

.2 

.8 

1.6 

.64 

3.24 

IID2 

.75 

.1 

.6 

.24 

1 .69 

[B3 

1.0 

.8 

1.6 

.64 

4.04 

l  in:; 

75 

.2 

.6 

.24 

1.79 

IB4 

2.0 

.8 

1.6 

.64 

5.04 

IID4 

.75 

1.0 

.6 

.24 

2.59 

[B5 

3.0 

.8 

1.6 

.64 

6.04 

[ID5 

.75 

2.0 

.6 

.24 

3.59 

IC1 

.02 

.6 

1.2 

.48 

2.30 

IIIA1 

3.0 

1.2 

.02 

.96 

5.18 

IC2 

.2 

.6 

1.2 

.48 

2.48 

TI1A2 

3.0 

1.2 

.10 

.96 

5.26 

[C3 

1.0 

.6 

1.2 

.48 

:;.2s 

IIIA3 

3.0 

1.2 

.20 

.96 

5.36 

IC4 

2.0 

.6 

1.2 

.48 

4.28 

IIIA4 

3.0 

1.2 

1.0 

.96 

6.16 

IC5 

3.0 

.6 

1.2 

.48 

5.28 

IMA.", 

3.0 

1.2 

2.0 

.96 

7.16 

11)1 

.02 

..". 

.0 

.24 

1.16 

1IIB1 

2.25 

.8 

.02 

.64 

3.71 

11)2 

2 

.3 

.6 

.24 

1.34 

IIIB2 

2.25 

.8 

.10 

.64 

3.79 

ID3 

1.0 

.3 

.6 

.24 

2.14 

II1B3 

2.25 

.8 

.20 

.64 

3.89 

ID4 

2.0 

.3 

.6 

.24 

3.14 

1 1 1  B4 

2.25 

.8 

1.0 

.64 

4.69 

ID5 

3.0 

.3 

.6 

.24 

4.14 

1 1 1 1 15 

2.25 

.8 

2.0 

.64 

5.69 

TTA1 

3.0 

.02 

2.4 

.96 

6.38 

IIH'l 

1.5 

.6 

.02 

.48 

2.60 

IIA2 

3.0 

.10 

2.4 

.96 

6.46 

niC2 

1.5 

.6 

.10 

.48 

2.68 

HA3 

3.0 

.20 

2.4 

.96 

6.56 

[IIC3 

1.5 

.6 

.20 

.48 

2.78 

TTA4 

3.0 

1.0 

2.4 

.96 

7.36 

1  1 1 ( '4 

1.5 

.6 

1.0 

.48 

3.58 

IIA5 

3.0 

2.0 

2.4 

.96 

8.36 

1 1 1 C5 

1.5 

.6 

2.0 

.48 

4.58 

[IB] 

2.25 

.02 

1.6 

.64 

1.51 

1111)1 

.75 

.:{ 

.02 

.24 

1.31 

1 1  B2 

2.25 

.10 

1.6 

.64 

t.59 

[IID2 

.75 

.:: 

.10 

.24 

l.::<» 

1 1 B3 

2.25 

.20 

1.6 

.64 

4.69 

nil).', 

.75 

.3 

.20 

.24 

1.49 

!  1 1 :  t 

2.25 

1.0 

1.0 

.64 

5.49 

iiidi 

.75 

.:i 

1.0 

.24 

2.29 

1 1 1 ::, 

2.25 

2.0 

1.6 

.64 

6.49 

1 1 1 1 ».-, 

.75 

.3 

2.0 

.24 

3.29 

348        University  of  California  Publications  in  Agricultural  Sciences    [Vol.1 

the  groups  of  a  series.  Thus  I  A  5,  IBS,  I  C  5,  and  I  D  5  each 
contained  3  grams  NaNO.,,  but  the  content  of  each  pot  in  K2S04 
was  2.4,  1.6,  1.2,  and  0.6  grams,  respectively;  hence  the  balance 
between  NaNO:,  and  K._,S04  is  very  different  in  each  of  the  four 
pots.  Table  1  shows  the  distribution  of  the  salts  in  the  three 
series  and  the  total  concentration  in  grams  of  the  salts  in  each 
pot.  The  total  quantity  of  nutrient  salts  was  added  to  the  sand 
at  the  beginning  of  the  experiment. 

The  plants  were  placed  in  the  sand  June  15  and  were  har- 
vested about  November  1,  the  tops  and  roots  being  kept  for  the 
determination  of  dry  weight.20  It  will  be  seen  that  the  plant 
was  allowed  sufficient  time  to  complete  its  natural  period  of 
growth,  thus  permitting  certain  observations  of  a  quantitative 
nature  as  recorded  in  table  2. 


PHYSIOLOGICAL  EFFECT  OF  NITROGEN 

Distribution  op  Salts  in  Series  I 
In  series  I  nitrogen  as  NaNO:,  was  the  salt  which  was  used 
in  the  same  weights  in  all  of  the  four  groups  A,  B,  C,  and  D, 
being  present  in  pots  1  to  5  as  follows:  0.01  g.  (.001  per  cent), 
0.2  g.  (.01  per  cent),  1.0  g.  (.05  per  cent),  2.0  g.  (.1  per  cent), 
3.9  g.  (.15  per  cent).  The  maximum  weights  of  other  salts  were 
Ca(H2P04)2,  1.2  g.;  K2S04,  2.4  g. ;  MgS04,  0.96  g.,  in  group  A, 
while  the  minimum  quantity  of  these  salts  as  added  in  group  D 
was  0.3  g.,  0.6  g.,  and  0.24  g.,  respectively.  The  total  concen- 
tration in  this  series  ranged  from  1.16  g.  in  I  D  1  to  7.56  g.  in 
I  A  5. 

Height  in  Series  I 
The  height  of  each  plant  was  measured  at  two  different 
periods.  The  first  measurement  was  made  when  the  majority 
of  the  plants  were  just  beginning  to  show  the  first  signs  of  flower- 
bud  formation.  The  second  measurement  was  taken  five  or  six 
weeks  later,  when  most  of  the  plants  were  in  full  bloom.  The 
final  height  of  the  five  plants  in  each  group  is  shown  graphically 


20  An   accident  to  the  roots  while  drying  prevented  the  collection  of 
further  data  on  their  dry  weight. 


1  !•  1 7 1      Juris:  Nutrient  Solution  on  Plants  Grown  in  Sand  I  ultures         349 

TABLE  2 

Si   MM.UIV   OF  QUALITATIVE  AND  Ql    \ '.  ill  'ATIVE    Data   for    EACB    PLANT 

in  the  following  table  the  roman  numerals  indicate  the  series  numbers, 
iiinl  the  tetters  are  those  of  the  corresponding  groups. 


Leal 

i  ,  .,i 

Dry 

Pot 

Height, 

length, 

width, 

\  umbi  i 

Number 

u  e    in 

No. 

cm. 

m 

cni. 

lea\  es 

flowers 

tups,  gms. 

IA1 

2.5 

7.6 

3.7 

(i. 

0. 

L.12 

IA2 

4.5 

9.6 

1  7 

7. 

0. 

L.60 

I  \  1 

8. 

lL'.l 

6.2 

10.5 

0. 

1.56 

l.\l 

57.5 

L3.8 

9.5 

17. 

25.5 

IA5 

15.5 

20.8 

10.2 

17.5 

24. 

7.83 

MM 

->.:, 

!•.:, 

4.9 

7.5 

0. 

1.29 

TB2 

3.5 

8.6 

4.1 

7. 

0. 

l.Ui 

II:;: 

8. 

12.1 

5.5 

9. 

1. 

2.17 

1R1 

7s. 

L8.8 

9.5 

17.5 

29. 

8.57 

1  nr. 

19. 

19.9 

10.1 

1 7.5 

21. 

7.96 

K'l 

3.5 

8.8 

4.3 

C.5 

0. 

.71 

Hi' 

2.5 

8.3 

4.3 

6. 

0. 

.79 

]c:: 

4.5 

11.2 

5.6 

7. 

0. 

L.65 

K'l 

94. 

19.5 

9.7 

17.15 

31.5 

l  <  15 

74. 

18.7 

9.1 

18. 

29. 

9.24 

1 1  >  l 

6.5 

in..-. 

5.4 

7. 

0. 

1.65 

TD2 

1  7..-» 

12.7 

6.3 

9.5 

0. 

L.53 

[D3 

59.5 

15.8 

7.8 

15. 

8.5 

5.86 

MM 

91.5 

14.6 

7.7 

19. 

34.5 

11.12 

1  1  >5 

66.5 

17.:: 

8.6 

18.5 

2 1 .5 

7.60 

TTA1 

15. 

L2.9 

6.4 

12. 

0. 

2.09 

IIA2 

55. 

1 8.5 

8.4 

15.5 

1  1.5 

6.21 

II  A:: 

69.5 

18.9 

9.4 

16.5 

22.5 

8.75 

1 1  A  4 

87. 

19.2 

9.7 

KI.5 

25.5 

S.5S 

IIA.-i 

73. 

18.9 

9.3 

16.5 

29. 

8.60 

[IB] 

21. 

i::.l 

6.1 

12. 

0. 

2.71 

HB2 

35.5 

15.3 

7.3 

1  1.5 

4.5 

3.82 

111::: 

43. 

15. 

7.4 

14. 

9.5 

4.1 

1 1 B4 

97. 

Is.:: 

9.3 

1  8.5 

37. 

9.3 

!  1 1 15 

74.5 

18.6 

9.6 

17. 

23.5 

7.76 

IK'l 

13.5 

12.2 

5.9 

11. 

0. 

2.73 

IIC2 

27.5 

L3.9 

6.6 

12. 

3. 

3.22 

lie:: 

101. 

L6.5 

8.2 

17.5 

34  5 

8.20 

IK'l 

90. 

17.3 

8.9 

17. 

32. 

8  66 

1 1  ( ■:, 

78. 

17.1 

8.3 

18. 

26.5 

7.88 

nni 

18. 

12.8 

6. 

1 1 .5 

2.5 

2.47 

JID2 

I',!.:, 

14.8 

7.4 

15.5 

15. 

5.83 

IID:: 

71. 

l. ;.:, 

7.6 

16. 

19.5 

6.27 

IIIM 

83.5 

l  1.2 

7.5 

17.5 

28. 

7.60 

1  1  1  »5 

Mi. 

L3.9 

7.2 

17. 

19. 

6.75 

1  1  1  A  1 

56.5 

L6.7 

8.0 

1  1  5 

6.5 

t.65 

[IIA2 

Mi.f, 

20. 

10.1 

16.5 

27. 

7.88 

III  A:: 

62. 

L'n. 7 

9.6 

17.5 

14. 

6.97 

IIIAI 

74. 

20.2 

Id. 

17. 

20.5 

10.53 

[IIA5 

63. 

22.1 

1(1.5 

17. 

•_'l. 

s.l  1 

350        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 


TABLE 

2—  (Cc 

mtinued) 

Leaf 

Leaf 

Dry 

Pot 

Height, 

length, 

width, 

Number 

Number 

weight 

No. 

cm. 

cm. 

cm. 

leaves 

flowers 

tops,  gins 

IIIB1 

81.5 

19.9 

10.1 

17. 

22. 

8.18 

IIIB2 

87. 

20.3 

10. 

17.5 

24. 

5.87 

IIIB3 

94.5 

18.3 

9.4 

17.5 

31. 

8.4 

IIIB4 

83. 

19.1 

9.7 

18. 

26.5 

4.86 

IIIB5 

77.5 

18.8 

9.7 

17. 

39.5 

8.42 

IIIC1 

89. 

18. 

9. 

17. 

18. 

6.58 

IIIC2 

102. 

17.7 

8.8 

17.5 

22.5 

8.57 

IIIC3 

109. 

17.4 

8.9 

18. 

23. 

9.4 

IIIC4 

88.5 

18.5 

9.2 

17.5 

25. 

7.66 

IIIC5 

79. 

17.2 

8.8 

18. 

26.5 

8.68 

IIID1 

89. 

16.4 

8.2 

17. 

14. 

5.6 

IIID2 

103.5 

15.1 

7.8 

18. 

17.5 

7.27 

IIID3 

100.5 

15.9 

7.8 

17.5 

16.5 

6.96 

IIID4 

90. 

16.5 

8.2 

17.5 

23. 

6.75 

IIID5 

66.5 

17.5 

8.7 

17.5 

19. 

6.36 

in  figure  1.  As  two  plants  were  given  similar  treatment  in  each 
case,  the  height  as  noted  in  table  2  is  the  mean  of  the  height 
measurements  of  these  two  plants. 


in 
90 

- 

/I 

80 

70 

- 

'              l   i 

6C 

- 

//   - 

N 

N 
N 
-« S 

50 

* 
/ 

//  /^ 

/ 

1       / 

^■~~~~^A 

40 

/ 

/ 

l<     / 

30 

20 

/ 
/ 

/ 

/ 

V 

11/ 
'/ 

10 

7 

/ 

'                                       ' 

i i 

, 

.001     .01  .05  .1  .15 

%  NaN03 
Fig.  1. — Graph  showing  the  influence  upon  height  of  equal  quantities 
of  NaN03  in  the  different  groups  of  series  I. 


1!U7|      Ayres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         ;  i  .">  1 

The  effect  of  increasing  the  <|u;uit  il  >•  of  nitrogen  from  planl 
1  to  planl  1  is  marked  in  all  groups.  In  every  group  plant  5 
is  not  so  tall  as  plant  4  (pi.  5),  hence  it  would  socio  that  the 
optimum  nitrogen  supply  for  tobacco  growing  in  sand  cultures, 
with  height  as  an  index,  is  somewhere  near  0.1  per  cent  of 
NaNO:!,  calculated   on  the  basis  of  the  dry  weight  of  the  sand. 


Cm. 


60  70 

Dg.  total  concentration 

Fig.  2. — Graph  showing  the  Influence  of  total  concentration  upon  height 
in  series  I. 


There  is  slight  variation  in  the  first  three  plants  of  groups  A, 
B,  and  C,  showing  that  change  in  the  total  concentration  of  the 
solution  within  these  limits  does  not  affect  the  characters  of 
the  plants  to  any  great  extent.  This,  however,  does  not  apply 
to  group  D,  in  which  the  total  concentration  is  low  (1.16  to 
4.14  g.),  for  plants  2  and  3  are  far  superior  to  the  corresponding 
plants  of  the  other  groups,  although  Hie  nitrogen  content  is 
exactly  the  same.    When  the  nitrogen  content  is  at  or  near  the 


352        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

optimum  the  influence  of  concentration  on  height  is  exhibited 
in  a  more  uniform  manner,  as  shown  in  plants  4  and  5  of  all 
groups  (pi.  6).  Plants  growing  in  the  solution  of  lower  concen- 
tration, in  general,  are  taller  than  those  growing  in  the  solutions 
of  higher  concentration. 

The  influence  of  total  concentration  upon  height  of  plant 
when  taken  in  connection  with  optimum  and  deficient  nitrogen 
supply  is  indicated  in  figure  2,  which  shows  a  curve  for  each  of 
the  two  measurements  made  on  each  plant,  the  upper  curve  being 
plotted  from  the  last  measurements  taken.  This  curve  is  espe- 
cially interesting  since  it  shows  the  influence  of  nitrogen  as  a 
prime  factor  in  growth  in  solutions  which  are  of  approximately 
the  same  concentration.  Thus  in  I  D  4  and  I  B  1,  where  the 
total  concentrations  are  3.14  g.  and  3.06  g.,  the  heights  of  the 
two  plants  are  91.5  cm.  and  5.5  cm.  Such  a  large  difference  can 
be  due  in  this  case  only  to  the  lack  of  nitrogen  in  I  B  1,  since 
there  is  present  a  considerable  excess  of  the  other  nutrients 
required  (pi.  7). 

A  study  of  the  early  and  late  height  curves  shows  that  the 
plant  responded  very  early  to  the  amount  of  salts  available,  as 
is  indicated  by  the  similarity  of  the  early  curve  to  that  based 
upon  the  later  measurements.  The  greatest  final  height  is  at- 
tained, as  was  to  be  expected,  through  the  continuous  growth 
of  those  plants  which  had  sufficient  nitrogen,  while  the  growth 
of  the  under-nourished  plant  was  decidedly  retarded.  Thus  at 
the  end  of  the  growing  season  the  differences  in  height  between 
the  two  groups  became  more  marked  as  the  time  of  complete 
maturity  drew  near.  Attention  is  called  to  this  fact  since  it  is 
not  an  uncommon  practice  in  growing  plants  in  water  cultures 
to  harvest  them  before  maturity.  While  these  plants  might  give 
an  index  of  the  influence  of  the  culture  solution  on  growth,  they 
would  not  give  a  true  value  for  the  nutritive  function  of  the 
solution,  since  increase  might  persist  for  a  considerable  time  in 
solutions  of  optimum  nutritive  value  while  plants  growing  in  an 
unfavorable  medium  would  be  practically  at  a  standstill. 


l!M7|        lyres:   Vutrieni  Solution  on  Plants  Grown  in  Sand  Cultures 

l>i;v  Weight  in  Series  I 

A  comparison  of  the  curves  for  heighl  (fig.  1)  and  for  <\ry 
weighl  (fig.  3)  shows  that  in  a  general  way  heighl  is  an  index  to 
the  dry  weight.  This  fad  is  more  marked  in  this  scries  than 
in  either  series  II  or  III  since  the  plants  were  more  uniform 
throughout  the  series,  being  uniformly  stocky  where  the  heighl 
was  above  40  cm.     In  the  other  groups  some  of  the  plants  were 


l  lecigi 

1  >r\    wt.  of  tops 


1  1  o 

In, 

/              ""'Vs. 

91 

■ 

y 

^"^".^ 

80 

■ 

/ 

^^ 

70 

y           / 

S"            Z^< 

CO 

■ 

/ 

S* 

50 

/          /        ^' 

40 

,/ 

/        ^    ^ — 

30 

/ 

/ 

A 

20 

s 

B 

y 

-Ss£^                            

_  C 

10 

— 

,/' 

_  — 

""■ 

_D 

*r-±-- 

, 

— ' 

— 

" 



^~" 

.001      .01 


.05 


.1  .15 

■  .   NaNOa 
Fig.  3. — Graph  showing  influence  of  equal  quantities  of  NaNO:.  in  the 
different  groups  of  series  I  upon  dry  weight  of  tops. 


tall  and  very  spindly  (pi.  15),  and  there  was  a  marked  decrease 
in  the  length  and  width  of  leaf,  which  would,  of  course,  lower 
the  dry  weight.  The  height  measurements  even  on  a  plant  of  the 
habit  of  the  tobacco  cannot  be  taken  alone  as  an  indication  of 
the  nutritive  value  of  a  solution,  a  fact  which  has  been  shown  to 
hold  true  to  a  much  more  noticeable  extent  in  such  plants  as 
wheat,  which  will  stool  more  in  some  cultures  than  in  others 
without  perceptible  differences  in  height. 

The  effect  of  the  concentration  is  evidenced  in  the  curve  for 
group  D,  which  is  much  higher  for  plants  3  and  4  than  for  plants 
of  like  number  in  any  other  groups.    Had  it  been  possible  to  take 


354        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

the  dry  weight  for  plant  I  C  4  this  weight  would  probably  have 
been  slightly  greater  than  that  of  I  D  4  (see  table  2),  making 
the  curves  correspond  to  those  for  height. 


THE  INFLUENCE  OF  THE  CULTUEE  SOLUTION  ON  FLOWEE 
PEODUCTION 

Our  information  concerning  factors  which  may  influence 
flower  formation  is  very  incomplete.  Vochting21  has  demon- 
strated that  light  intensity  is  a  factor  in  flower  development  in 
Mimulus,  and  numerous  other  plant  physiologists  have  found 
that  a  more  or  less  marked  influence  on  flower  formation  could 
be  correlated  with  some  external  factor.  The  relation  to  the 
formation  of  flowers  of  nuti'ient  salts  in  the  medium  in  which 
growth  takes  place  seems  never  to  have  been  studied  in  any 
thoroughgoing  manner.  Mobius22  found  that  certain  Oramineae 
flowered  better  on  dry  soil  and  on  soil  low  in  nutrient  elements 
than  on  soil  rich  in  nutrients  and  where  water  supply  was 
abundant.  Jost23  thinks  that  the  fact  that  root  pruning  increases 
flower  production  may  be  thus  explained,  since  there  is  a  lower- 
ing of  the  absorptive  capacity  of  the  tree  for  inorganic  salts. 
There  has  been  also  a  general  opinion,  which  is  not  fully  justified, 
that  any  condition  which  will  cause  marked  vegetative  develop- 
ment will  retard  flower  production.  The  experiment  herein  re- 
ported has  presented  an  opportunity  for  a  study  of  the  influence 
of  the  composition  and  concentration  of  the  solution  upon  flower 
production. 

In  the  plant  used  in  this  experiment  the  flowers  fall  soon 
after  opening,  leaving  a  scar  upon  the  inflorescence  stock.24  At 
the  end  of  the  growing  season  the  number  of  flowers  produced 
by  each  plant  was  determined  by  counting  these  scars  (see  table 
2).  The  total  number  of  flowers  produced  by  each  plant  is  shown 
diagrammatically  in  figure  4. 


2i  Vochting,  Jahrb.  f.  wiss.  Bot.,  vol.  25,  p.  149,  1893. 

22  Mobius,  Beitr.  z.  Lehre  v.  d.  Fortpflanzung  d.  Gewachse,  Jena,  1897. 

23  Jost,  Lectures  on  plant  physiology,  p.  364,  1907. 

24  Goodspeed  and  Ayres,  Univ.  Calif.  Publ.  Bot.,  vol.  5,  no.  9,  1916. 


1017  |      Ayres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         355 


.i.z.Jt^li^l^Ukli.g.JHbli^l^UN        jhbM'ibLi'NilbMslibbUj         li  bbUlai  bbULsl  i  bbUNi  I2I3I4I5 


Group  j\ 


B  C 

Series  I 


ABC 

Series  II 


A  B  c  D 

Series  III 


Fi£.  4. — Diagrammatic  representation  of  the  number  of  flowers  produced 
by  each  plant  in  series  I,  II,  and  111. 


Flower  Production  in  Series  I 
The  nitrogen  supply  is  seen  to  have  a  very  definite  influence 
upon  flower  production.  In  series  I  no  flowers  were  produced 
by  plants  1  and  2  of  any  group  and  in  only  two  groups  were 
any  flowers  produced  by  plant  3,  showing  definitely  that  unless 
nitrogen  is  present  in  excess  of  0.05  per  cent  as  NaNO:i  the  under- 
nourished tobacco  plant  will  not  flower.     Flower  production  in 


356        University  of  Col i font ia  Publications  in  Agricultural  Sciences   [Vol.1 

general  corresponded  to  vegetative  vigor,  the  plant  exhibiting 
maximum  vegetative  growth  producing  the  largest  number  of 
flowers.  Here  again  the  influence  of  the  total  concentration  of 
the  solution  was  apparent  in  the  flower  yield  in  the  various 
groups,  which  increased  as  the  concentration  decreased. 


Cm. 
100 

~~~"""-^                           '"'v 

90 

1 

^  7^-l\ 

80 

"f  / 

70 

fiO 

-  \h         ' 

1          ' 

\      ' 

1         1 

;>o 

11  <' 

\\\    / 

•  1  ' 

1     / 

40 

If 

:io 

r 
f 

V 

20 

1 

\ 

10 

1 — 1 1 1                                                 1 

g  g  S  .05  .1    '/(  CafH-.PO^j 

o  o     ■ 

Fig.  5. — Graph  showing  the  influence  upon  height  of  equal  quantities 
of  Ca(H2P04)2  in  the  different  groups  of  series  II. 


PHYSIOLOGICAL  EFFECT  OF  PHOSPHORUS 
Distribution  op  Salts  in  Series  II 
In  series  II  a  study  was  made  of  the  influence  of  phosphorus 
added  as  Ca(H2P04)2.  This  salt  was  present  in  the  same  quan- 
tity in  all  groups  A,  B,  C,  and  D,  the  quantity  in  each  of  the  pots 
1  to  5  being  0.02  g.  (.001  per  cent),  0.1  g.  (.005  per  cent), 
0.2  g.  (.01  per  cent),  1.0  g.  (.05  per  cent),  2.0  g.  (.1  per  cent), 


1917]      Ayres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         '■'•'<• 

respectively.  The  maximum  weights  (if  (lie  oilier  sails  were 
NaN03,  ::  g. ;  K  so,.  2.4  g.;  MgS04l  0.96  g.,  in  group  A,  while  the 
minimum  quantities  of  these  salts  as  added  in  group  D  were 
0.7")  g.,  0.6  g..  and  0.24  g.,  respectively.     The  total  concentration 

in  this  scries  ranged  from   1.01  g.  to  <>.:>s  <>■. 


10  - 


70  80 

Us.  total  concentration 

Fig.  6. — Graph  showing  the  influence  of  total  concentration  upon  height 
in  series  II. 


Height  in  Series  11 

Figure  5  shows  the  height  curves  for  the  five  plants  of  each 
of  the  four  groups  in  this  series.  There  is  clear  indication  thai 
the  optimum  phosphorus  supply  lies  somewhere  between  .05  per 
cent  and  .01  per  cent  of  Ca(H2P04)2,  the  heighl  of  plant  4  heing 
greatest  when  all  groups  are  considered.  The  difference  in  height 
between  plants  4  and  5  is  not  great  in  any  group.  The  effect  of 
increasing  the  quantity  of  Ca(H2P04)2  is  clearly  seen  in  plants 
1,  2,  3,  and  4  of  groups  A,  B,  and  D  (pi.  8).    The  effect  of  t ota I 


358        University  of  California  Publications  in  Agricultural  Sciences    [Vol.1 


concentration  in  this  series  is  not  so  marked  as  in  series  I,  but 
is  slightly  evidenced  in  the  somewhat  better  growth  of  some  of 
the  plants  in  groups  C  and  D  as  compared  with  plants  in  groups 
A  and  D  (pi.  9).  The  height  of  the  plants  at  two  different 
periods  in  their  growth  was  taken  in  this  series  at  the  same  time 
that  the  measurements  were  taken  in  series  I  and  plotted  against 
total  concentration  (fig.  6).  The  total  concentration  of  salts  in 
the  solution  is  here,  as  in  series  I,  of  secondary  importance  when 
one  element  is  present  in  insufficient  amount,  as  will  be  seen 
(pi.   6)    when  plant   II  C  1    (3.20  g.)    is  compared   with   II  C  3 

Decigrams. 
Dry  wt.  of  tops 
100 


.l'i        Ca(H2P04)L. 


Fig.  7. — Graph  showing  the  influence  on  dry  weight  of  tops  of  equal 
quantities  of  Ca(H2P04),  in  the  different  groups  of  series  II. 

(3.38  g.).  While  the  total  concentration  is  practically  the  same 
and  the  total  quantity  of  each  of  the  other  salts  is  the  same  the 
Ca(H.,P04)1,  in  II  C  3  is  ten  times  the  quantity  of  the  same  salt 
in  II  CI. 

Dry  Weight  in  Series  II 
A  comparison  of  height  (fig.  5)  and  dry  weight  curves  (fig.  7) 
for  tops  in  this  series  shows  that  height  here  is  not  an  accurate 
index  to  dry  weight.  Thus  group  A  gave  the  greatest  total  dry 
weight,  while  the  greatest  total  height  of  plants  occurred  in 
group  D,  a  fact  which  is  explicable  since  very  serious  injury 
resulting  in  a  spindly  habit  was  shown  by  many  plants  in  the 
D  group,  as  will  be  pointed  out  later  in  the  discussion  of  injury 
due  to  the  improper  balance  of  salts  in  the  solution. 


L917]        lyres:  Nutrient  Solution  on  Plants  Groun    in  Sand  Cultures  359 

Flower  Production  in  Series  1 1 
The  total  number  of  flowers  produced  in  this  series  was  Larger 
ilian  in  series  I.  due  largely  to  the  fad  thai  there  was  less  stunted 
growth  in  plants  ].  2,  and  3  of  each  group,  for  which  an  ample 
supplj  of  nitrogen  was  available.  Plants  [I  A 1,  II  B 1,  and 
Ilt'l  did  not  produce  any  flowers.  The  greatesl  number  of 
flowers  was  formed  in  group  C  and  the  greatesl  yield  of  any  one 
plant  was  given  by  II  B  5.  The  flower  yield  in  each  group  is 
definitely  related  to  the  general  character  of  the  plant  as  men- 
t ioned  above  in  conned  ion  \\  ith  series  I. 

PHYSIOLOGICAL  EFFECT  OF  POTASSIUM 

DisTinra  thin  op  Salts  in  Skkiks  I  IT 
The  plants  in  series  III  were  grown  to  study  the  physiological 
influence  of  various  quantities  of  potassium  added  as  K.S(),  in 
the  presence  of  a  sufficient  supply  of  other  nutrient  sails,  fol- 
lowing the  same  plan  as  outlined  above  for  the  variation  of 
nitrogen  and  phosphorus  in  series  I  and  II.  K..XO,  was  present 
in  the  same  weight  in  each  of  the  four  groups  A,  B,  C,  and  I), 
the  quantities  added  to  each  of  the  pots  1  to  5  being  0.02  g. 
(.001  per  cent),  0.1  g.  (.005  per  cent),  0.2  g.  (.01  per  cent),  1.0  g. 
.().">  per  cent),  and  2.0  g.  (.1  per  cent).  The  maximum  weights 
of  the  other  salts  were  \'a.\<>  ,  :;  g.;  Ca(HJPOJ2,  1.2  g. ;  MgS04, 
0.96  g.,  in  group  A.     In  group   I)  the  minimum   quantities  of 

these  salts  were  0.75  g.,  0.3  g.,  and  0.24  g.,  respectively.  The 
total  concentration  in  this  series  varied  from  1.31  g.  to  7.16  g. 

Height  in  Series  III 
No  plants  in  this  series  were  less  than  f>0  cm.  high,  due  to 

the  fact  that  the  two  nutrient  elements,  nitrogen  and  phosphorus. 
which  in  the  order  named  are  of  first  importance  as  growth 
factors,  were  present  in  sufficient  quantity  to  insure  considerable 
growth  (pi.  7).  Only  a  small  quantity  of  K,S04  (.005  to  .01 
per  cent  )  was  required  in  this  series  to  give  plants  of  maximum 
In  ight,  hence  the  curves  show  a  downward  trend  in  all  plants 
after  either  plant  2  or  plant  3  in  each  group  (fig.  8,  also  pi.  12). 
Thus  it  is  evident  that  there  is  a  toxic  effect  of  an  excess  of 
potassium,  irrespective  of  the  total  concentration  of  the  solution. 


360        University  of  California  Publications  in  Agricultural  Sciences    [.Vol.  1 

The  influence  of  total  concentration  is  again  plainly  seen  in 
this  series.  Plate  13  shows  plant  1  of  each  of  the  groups  A,  B, 
C,  and  D.  As  the  total  concentration  decreases  from  A  to  C 
there  is  a  steady  increase  in  the  vigor  of  the  plant  as  judged  by 
height.  Curves  in  figure  9  indicate  this  general  tendency  to  an 
increase  of  height  with  a  decrease  in  the  total  concentration  of 
the  solution. 

Dry  Weight  in  Series  III 
As  in  series  I  and  II,  the  dry -weight  curves  (fig.  10)  do  not 
correspond  with  the  height  curves  (fig.  8).  The  greatest  dry 
weight  of  any  plant  was  that  of  III  A  4,  which  was  not  so  tall  as 
the  other  plants  of  like  number.  The  low  dry  weight  of  III  B  4 
is  especially  noticeable.  A  comparison  of  the  two  dry-weight 
curves  for  the  A  and  B  groups  shows  a  very  peculiar  effect  of 
K2S04  in  solutions  of  different  balance.  In  each  case  where  the 
group  A  curve  is  high,  the  group  B  curve  is  low,  a  fact  which 
also  applies  to  plants  3,  4,  and  5  in  the  A  and  C  groups.  That 
this  should  occur  with  such  regularity  is  rather  remarkable  and 
no  satisfactory  explanation  can  as  yet  be  found  to  account  for 
this  situation.  It  is  evident  that  the  physiological  balance  of 
salts  in  the  solution  is  dependent  upon  the  concentration,  as  has 
been  shown  by  McCool,25  Gile,20  Tottingham,27  and  Shive.28 

Flower  Production  in  Series  III 

The  more  vigorous  growth  of  plants  in  this  series  gave  a 

greater  total  yield  of  flowers  than  either  of  the  other  two  series. 

This  was  to  be  expected  from  the  result  of  series  I  and  II,  where 

the  flower  yield  was  shown  to  be  definitely  related  to  the  general 

vigor  of  the  plants.     The  production  of  flowers  in  this  series 

differs,  however,  from  that  in  the  other  series.     An  increase  of 

K.,S04,  while  in  general  depressing  the  total  height  of  the  plant, 

when  added  in  excess  of  .01  per  cent  gave  a  higher  flower  yield. 

Thus  in  group  C  there  is  steady  increase  in  the  number  of  flowers 

produced   which   corresponds   to  the   increase   of   K2S04.      The 

25  McCool,  Cornell  Agric.  Exp.  Sta.  Mem.,  vol.  2,  pp.  121-170,  1913. 
ze  Gile,  Porto  Rico  Agric.  Exp.  Sta.  Bull.  12. 

27  hoc.  cit. 

28  Loc.  cit. 


1917]      Ayres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         381 


Cm.  r 


ion 


%  K2S04 


Fig.  8. — Graph  showing  the  influence  upon  heighl  of  equal  quantities 
,i|'   K  SO,   hi    tin'  .lil't'rniit    groups  of  series    III. 


Cm. 
110 


90 


so 


60 


in 


::o 


jii 


J_ 


20  30  10  50  60  70 

Dg.  total  concentral  ion 
Fig.  9. — Graph  showing  the  influence  upon  height  of  total  concentration 
in  series  III. 


362        University  of  California  Publication*  in  Agricultural  Sciences    [Vol.  1 


greatest  flower  production  occurred  in  group  B,  and  plant  5  of 
this  group  produced  a  larger  number  of  flowers  than  any  other 
plant  in  any  series. 

INJURY  DUE  TO  EXCESS  OR  DEFICIENCY  OF  NUTRIENT  SALTS 

The  deficiency  or  excess  of  certain  elements  will  cause  injury 
which  is  very  characteristic.  Gris  as  early  as  1843  showed  that 
chlorosis  was  caused  by  a  lack  of  iron  in  the  nutrient  solution. 
Nitrogen  starvation  likewise  has  long  been  known  to  cause  chlo- 
rosis, a  condition  which  may  also  result  from  an  excess  of  soluble 

Decigrams. 
Dry  wt.  of  tups 
Cm. 


',    K_.su, 

Fig.   10. — Graph  showing  the  influence  upon  dry  weight  of  tops  of  equal 
quantities  of  K_S04  in  the  different  groups  of  series  III. 

phosphate.29  Magnesium  starvation  results  in  injury  to  the 
chlorophyll  bodies,  and  in  excess  is  harmful  unless  antagonized 
by  calcium.30  Other  physiological  disturbances  not  so  well  estab- 
lished as  these  mentioned  have  been  considered  to  be  associated 
with  a  deficiency  or  excess  of  nutrient  elements. 

The  most  marked  indication  of  the  fact  that  certain  cultures 
in  this  experiment  did  not  furnish  a  normal  medium  for  growth 
was  seen  in  the  chlorosis  which  is  so  characteristic  of  plants 
grown  in  solutions  which  are  deficient  in  nitrogen.  This  type 
of  injury  was  uniformly  present  in  all  cultures  containing  1.0  g. 
or  less  of  NaNO.,,  but  was  especially  marked  in  series  I,  plants 
1,  2,  and  3,  of  all  groups.     It  is  not  possible  to  draw  a  sharp 

29  Crone,  Sitzungsber  Neiderrhein.  Ges.  Nat.-  und  Heilk,  Bonn,  1902, 
pp.  167-173. 

3»Loew  and  May,  U.  S.  Dept.  Agrio.  Bur.  Plant  Ind.  Bull.  1,  1901. 


L917]        lyres:   Vutrient  Solution  on  Plants  Grown  in  Sand  Cult  363 

line  which  will  clearly  segregate  the  injury  to  the  various  plants 
of  a  Large  scries  of  this  kind  into  well-defined  groups  since  there 
is  always  more  or  less  overlapping.  An  attempt  was  made,  how- 
ever, to  divide  the  plants  into  groups  which  would  shew  in  each 
case  a  characterisl ic  type  of  injury. 

(a)  This  »roup  was  made  up  of  plants  which  were  very  much 
stunted,  being  less  than  8  cm.  in  heighl  and  in  every  ease  showed 
a  marked  chlorosis  which  was  clearly  attributed  to  a  low  supply 
of  nitrogen.     The  plants  in  this  group  were  I  A  1,  I  A  2,  I  A  3, 

I  B  1.  I  P.  2,  I  B3,  [CI,  1  C2,  I  C3,  1  I)  1. 

(b)  This  group  was  somewhat  taller,  from  13  to  21  cm.  high, 
hut  clearly  stunted  in  growth.  These  plants  showed  less  chlo- 
rosis, since  nitrogen  was  present  in  sui'licient  quantity  to  provide 
close  to  the  optimum  supply  in  all  cultures  with  the  exception 
of  II  I)  I  and  I  1)2,  where  there  was  a  distinct  chlorosis  due  to 
the  low  nitrogen  supply.  Plants  showing  this  type  of  injury  were 
II A 1,  II Bl,  II  CI,  II Dl,  ID 2. 

(c)  Plants  in  this  group  showed  a  more  serious  type  of  injury 
than  any  of  the  other  plants.  They  were  more  than  40  cm.  in 
height,  but  were  very  spindly  (pi.  15).  The  whole  plant  showed 
marked  chlorosis,  which  affected  the  lower  leaves  most  severely 
and  soon  resulted  in  their  death.  This  type  of  plant  was  found 
in  cultures  [  D  3,  II  B  2,  II  B  3,  II  C  2,  111)2.  [I  D  3,  1 1  D  4, 
III  1)  1.  Ill  1)2.  Ill  1)3,  HID  4,  and  III  D  5. 

(d)  The  plants  of  this  group  were  decidedly  more  vigorous 
than  those  of  the  preceding  groups,  as  indicated  by  their  in- 
creased height  and  better  color.  Indeed,  they  seemed  to  he  per- 
fectly normal.  The  following  cultures  were  classed  in  this  group : 
IC4,  11)4,  lie:?,  IIC  4,  II  D  5,  III  A  1,  III  A  2,  III  A  3, 
Til  B  1.  IIIB2,  IIIB3,  III  CI,  III  C  2,  III  C  3,  I1IC4,  [II  C  5 
The  following  plants  were  even  better  in  appearance  than  those 
just  named  :  I A  4,  I  A  5,  I  B  4,  I  B  5,  I  C  5,  I  D  5,  II  A  2,  II  A  3, 

II  A  4,   II  A  5,   II  B  4,   II  B  5,   II  C  5,   1 1 1  A  4.   Ill  A  5,    1 1 1  P»  4. 

III  B  5. 

A  study  of  the  above  grouping  indicates  that  chlorosis  was 
present  wherever  the  nitrogen  content  was  low,  as  was  to  be  ex- 
pected. The  spindly  growth  characteristic  of  groups  II  D  and 
III  I)  may  also  be  due  to  the  low  supply  of  nitrogen.     It  seems 


364        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

that  the  injury  which  was  so  marked  in  series  II  must  be  in  some 
way  associated  with  the  calcium-magnesium  content  in  solutions 
which  were  not  properly  balanced.  No  definite  calcium-magne- 
sium ratios  can  be  found  which  are  responsible  for  the  injury 
which  occurred  in  this  series.  Twenty  different  calcium-magne- 
sium ratios  ranging  from  0.035  to  3.54  occur  in  the  series,  and 
both  plants  which  were  normal  and  plants  which  were  seriously 
injured  were  found  in  cultures  in  which  the  calcium-magnesium 
ratio  was  low  as  well  as  in  cultures  where  this  ratio  was  high. 
No  definite  conclusions  can  be  drawn  in  this  connection,  however, 
since  the  other  variables  present  complicate  the  situation  so  that 
the  injury  cannot  be  said  with  certainty  to  be  associated  with  an 
improper  balance  between  the  calcium  and  magnesium. 

TABLE  3 

Summary  of  Complete  Experiments 

Grouped  in  such  a  manner  that  comparison  can  be  made  with  special 
reference  to  the  influence  of  concentration  and  balance  of  the  solution 
upon  crop  and  flower  production.  The  calculation  of  the  per  cent  total 
concentration  is  based  on  the  assumption  that  the  salts  are  all  dissolved 
in  the  quantity  of  water  held  by  2000  grams  of  sand  when  saturated.  To 
get  this  value  in  parts  per  million,  multiply  the  total  concentration  in 
grams  by  227.2.  The  real  concentration  would  be  much  greater  than  these 
values  would  indicate,  since  the  sand  was  not  kept  saturated. 


Series 

I 

« 

et 

o 

P.    <D    - 

o>  o  £ 

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O 

oa 

«  CD 

CO 

da 

_-a 

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s  8 

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EH 

TA1 

.02 

.001 

1.2 

2.4 

.96 

4.58 

1.04 

2.5 

1.12 

0. 

IB1 

.02 

.001 

.8 

1.6 

.64 

3.06 

.69 

5.5 

1.29 

0. 

IC1 

.02 

.001 

.6 

1.2 

.48 

2.30 

.52 

3.5 

.74 

0. 

ID1 

.02 

.001 

.3 

.6 

.24 

1.16 

.26 

6.5 

1.65 

0. 

IA2 

.2 

.01 

1.2 

2.4 

.96 

4.76 

1.08 

4.5 

1.6 

0. 

IB2 

.2 

.01 

.8 

1.6 

.64 

3.24 

.73 

3.5 

1.40 

0. 

IC2 

.2 

.01 

.6 

1.2 

.48 

2.48 

.56 

2.5 

.79 

0. 

ID2 

.2 

.01 

.3 

.6 

.24 

1.34 

.30 

17.5 

1.53 

0. 

IA3 

1.0 

.05 

1.2 

2.4 

.96 

5.56 

1.26 

8. 

1.56 

0. 

IB3 

1.0 

.05 

.8 

1.6 

.64 

4.04 

.91 

8. 

2.17 

1. 

IC3 

1.0 

.05 

.6 

1.2 

.48 

3.28 

.74 

4.5 

1.65 

0. 

ID3 

1.0 

.05 

.3 

.6 

.24 

2.14 

.48 

59.5 

5.86 

8.5 

IA4 

2.0 

.1 

1.2 

2.4 

.96 

6.56 

1.35 

57.5 

25.5 

IB4 

2.0 

.1 

.8 

1.6 

.64 

5.04 

1.14 

78. 

8.57 

29. 

IC4 

2.0 

.1 

.6 

1.2 

.48 

4.28 

.97 

94. 

31. 

ID4 

2.0 

.1 

.3 

.6 

.24 

3.14 

.71 

91.5 

11.12 

34.5 

IA5 

3.0 

.15 

1.2 

2.4 

.96 

7.56 

1.71 

45.5 

7.83 

24. 

IB5 

3.0 

.15 

.8 

1.6 

.64 

6.04 

1.37 

49. 

7.96 

21. 

IC5 

3.0 

.15 

.6 

1.2 

.48 

5.28 

1.20 

74. 

9.24 

29. 

ID5 

3.0 

.15 

.3 

.6 

.24 

4.14 

.94 

66. 

7.60 

21.5 

1917]      Ayres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures 


365 


Series 

II 

d 
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0. 

IIB1 

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2.25 

1.6 

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4.51 

1.02 

21. 

2.71 

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3.20 

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2.73 

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1.61 

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18. 

2.47 

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2.4 

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6.46 

1.46 

55. 

6.21 

14.5 

IIB2 

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2.25 

1.6 

.64 

4.59 

1.04 

35.5 

3.82 

4.5 

IIC2 

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1.5 

1.2 

.48 

3.28 

.74 

27.5 

3.22 

3. 

1  1  1  >U 

.10 

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.75 

.6 

.24 

1.69 

.38 

64.5 

5.83 

15. 

IIA3 

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.96 

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1.49 

69.5 

8.75 

22.5 

J I  ]',.'. 

.20 

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1.6 

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4.69 

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43. 

4.11 

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.01 

1.5 

1.2 

.48 

4.18 

.94 

101. 

8.20 

17.5 

IID3 

.20 

.01 

.75 

.6 

.24 

2.59 

.58 

74. 

6.27 

16. 

IIA4 

1.0 

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3. 

2.4 

.96 

7.36 

1.67 

87. 

8.58 

25.5 

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2.25 

1.6 

.64 

5.49 

1.24 

97. 

9.3 

37. 

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1.5 

1.2 

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4.18 

.95 

90. 

8.66 

32. 

IID4 

1.0 

.05 

.75 

.6 

.24 

2.59 

.58 

83.5 

7.60 

28. 

IIA5 

2.0 

.1 

3. 

2.4 

.96 

8.36 

1.90 

73. 

8.60 

29. 

IIB5 

2.0 

.1 

2.25 

1.6 

.64 

6.49 

1.47 

74.5 

7.76 

23.5 

IIC5 

2.0 

.1 

1.5 

1.2 

.48 

5.18 

1.17 

78. 

7.88 

26.5 

1 1 1  )5 

2.0 

.1 

.75 

.6 

.24 

3.59 

.81 

86. 

6.75 

19. 

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. 


366        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

THE  ABSORPTION  OF  SALTS  FROM  THE  CULTURE  MEDIUM 

The  absorption  by  plants  of  salts  from  a  solution  is  no  doubt 
intimately  related  to  the  composition  of  the  solution,  since  the 
intake  of  inorganic  salts  occurs  only  when  the  concentration  of 
the  solute  outside  the  permeable  protoplast  is  greater  than  that 
within.  Hence  the  total  osmotic  concentration  of  a  solution  may 
affect  the  intake  and  storage  of  the  salts  from  the  solution.31 
The  quantity  of  salts  which  are  absorbed  by  the  plant  may  also 
vary  with  the  qualitative  composition  of  the  solution.  Thus  True 
and  Bartlett82  have  shown  that  absorption  from  a  solution  of  two 
or  of  three  salts  is  more  rapid  than  from  a  solution  containing 
a  single  salt.  It  is  evident  that  the  factors  which  regulate  ab- 
sorption are  very  complex,  and  that  this  complexity  increases 
with  an  increase  in  the  number  of  different  anions  and  cations 
in  the  solution.  It  is  further  evident  that  two  methods  may  be 
followed  with  a  view  to  ascertaining  the  quantities  of  salts  ab- 
sorbed. The  ash  of  the  plants  may  be  analyzed  or  the  residue 
of  salts  remaining  in  the  culture  may  be  determined.  It  has 
seemed  desirable  to  attempt  a  study  of  absorption  in  the  present 
case  by  means  of  the  latter  method. 

Method  of  Analysis 

The  small  quantities  of  salts  added  to  each  pot  made  the 
acid-extraction  method  undesirable,  since  the  large  quantities  of 
sand  required  to  give  weighable  precipitates  would  have  been 
extremely  hard  to  dehydrate,  thus  introducing  a  considerable 
source  of  error.  For  this  reason  the  colorimetric  method  of 
analysis13  was  used  in  this  work.  An  exception  was  made  in  the 
determination  of  calcium,  which  was  made  by  the  usual  volu- 
metric method.  The  sulphur  was  determined  gravimetrically  as 
BaS04.  A  water  extract  was  prepared  from  250  g.  of  sand  by 
leaching  with  successive  small  portions  of  distilled  water  until 


si  Livingston,  The  role  of  diffusion  and  osmotic  pressure  in  plants, 
Chicago,  1903. 

32  True  and  Bartlett,  U.  S.  Dept.  Agric.  Bur.  Plant  Ind.  Bull.  231,  1912, 
and  Am.  Jour.  Bot.,  vol.  2,  pp.  255-278,  311-323,  1915,  vol.  3,  pp.  47-58, 
1916. 

13  Schreiner  and  Failyer,  U.  S.  Dept.  Agric.  Bur.  Soils,  Bull.  31,  1906. 


<) 


1911  j      Ayres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         307 

500  c.c.  had  been  used.  The  filter  containing  the  sand  was  thru 
allowed  to  stand  for  about  fifteen  hours,  and  the  sand  was  Leached 
with  another  500  c.c.  portion  of  water.  The  filtrate  was  evapor 
ated  to  dryness,  the  residue  dehydrated  at  100°  C,  and  strongly 
ignited  in  a  platinum  dish  to  destroy  organic  matter.  The  resi- 
due was  then  dissolved  in  hot  water  and  made  up  to  definite 
volume  from  which  aliquot  portions  were  taken  for  analysis.  A 
2000  g.  sample  of  the  washed  sand  used  in  the  experiment  gave 
by  this  method  the  following  analysis: 

N  K  P  Mg  Ca  S 

00.       33.6       5.2       06.4       2.4       15.6  milligrams 

In  this  analysis,  as  well  as  in  all  the  following  analyses,  the 
statement  made  is  for  the  total  weight  in  milligrams  of  the 
element  contained  in  2000  g.  of  sand,  which  was  the  quantity 
contained  in  each  pot.  Table  4  gives  a  summary  of  the  analysis 
of  each  of  the  sixty  samples  of  sand  used.  The  total  quantity 
of  each  element  present,  calculated  from  the  quantities  of  salts 
added  plus  the  quantity  in  the  original  sand,  is  given,  as  well  as 
the  number  of  milligrams  of  the  element  missing  from  the  pot  at 
the  end  of  the  growing  season.  This  latter  value  is  the  difference 
between  the  total  weight  of  the  elements  present  and  the  residue 
as  shown  by  the  analysis  of  the  water  extract.  The  difference 
thus  obtained  represents  the  quantity  of  the  element  absorbed 
by  the  plant  and  adsorbed  by  the  sand  particles.  It  must  be 
admitted  that  it  is  not  known  just  how  great  a  factor  adsorption 
may  be  in  the  case  of  this  sand. 

Discussion  of  Results 

In  series  I  no  nitrogen  as  nitrate  remained  in  pots  1,  2,  3,  and 
4  of  groups  A,  B,  and  C.  In  group  D  there  is  a  small  residue  of 
nitrogen  in  spite  of  the  fact  that  the  total  crop  production  was 
greatest  in  this  group.  The  concentration  of  the  solution  clearly 
affects  the  economical  use  of  nitrogen,  a  fact  which  in  general 
is  also  indicated  in  series  II  and  in  series  III.  It  is  especially 
noticeable  that  there  is  a  much  larger  quantity  of  nitrogen  left 
in  series  III  D  than  in  either  series  I  D  or  II  D.  The  total  crop 
production  for  group  III  D  was  better  than  that  of  the  D  group 


368        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 


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370        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

in  either  of  the  other  series,  a  result  which  is  explicable  since 
nitrogen  is  a  more  important  limiting  factor  than  phosphorus, 
and  phosphorus  is  in  turn  more  important  as  a  limiting  factor  in 
growth  than  potassium.  Hence  in  a  solution  where  nitrogen  is 
deficient,  and  potassium  and  phosphorus  present  in  optimum 
amounts,  a  smaller  crop  production  results  than  is  the  case  where 
phosphorus  is  the  deficient  factor.  A  deficiency  of  potassium 
does  not  so  seriously  affect  the  intake  of  other  salts,  with  the 
result  that  a  better  crop  is  produced  than  is  the  case  where 
phosphorus  is  the  deficient  factor. 

The  method  of  analysis  which  it  was  necessary  to  use  makes 
the  analytical  values  for  phosphorus  and  magnesium  rather  un- 
reliable. In  series  II,  where  phosphate  was  added  in  increasing 
quantities  from  pot  1  to  pot  5  in  each  group,  the  analysis  of  the 
water  extract  shows  the  effect  of  this  increment.  It  will  be 
noticed  that  the  analytical  values  are  all  of  about  the  same  order 
of  magnitude,  winch  may  point  strongly  to  adsorption  by  the 
sand.  No  general  conclusion  as  to  the  adsorption  of  phos- 
phorus and  of  magnesium  can  be  drawn  for  the  reasons  above 
enumerated. 

In  the  ease  of  potassium  the  method  of  analysis  was  much 
more  accurate.  There  is  evidence  in  series  I,  groups  A,  B,  C, 
and  D,  of  an  increase  in  the  amount  of  potassium  absorbed  which 
in  general  seems  to  be  related  to  the  more  vigoi'ous  growth  re- 
sulting from  the  increasing  quantities  of  nitrogen  as  added  in 
these  groups.  A  similar  relation  holds  in  the  other  two  series, 
as  will  be  seen  from  the  ratios  between  potassium  added  and 
potassium  remaining,  which  are  higher  where  the  nitrogen  is 
added  in  large  quantities  than  is  the  case  where  this  element  was 
present  in  small  quantities.  The  high  ratios  of  potassium  added 
to  potassium  remaining  after  growth,  therefore,  usually  occur 
where  the  dry  weight  is  highest. 

Not  much  can  be  said  on  the  absorption  of  calcium.  In 
series  I  it  is  noticeable  that  the  quantity  of  calcium  remaining, 
as  compared  in  the  four  groups  of  this  series,  bears  an  inverse 
relation  to  the  calcium  added.  Less  calcium  is  absorbed  from 
the  solutions  of  low  total  concentration  than  from  those  which 
have    a    high    concentration.      Since    the    crop    production    was 


101 


l!il7|      Ayres:  Nutrient  Solution  on  Plants  Gro  Sand  Cultures         .'!71 

greater  in  group  I),  the  calcium  must  have  been  used  with  greater 
economy  in  this  group  where  the  total  concentration  was  low. 

The  Large  aumber  of  variables  which  are  presenl  in  each  of 
the  solutions  make  accurate  deductions  concerning  the  exact  re- 
lation between  any  element  and  the  growth  of  the  plant  almost 
impossible.  In  fact,  growth  lias  been  shown  to  be  influenced  i 
by  one  factor  alone  but   by  combinations  of  factors. 


GENERAL  DISCUSSION 
It  is  evident,  as  noted  above,  that  the  large  number  of  vari- 
ables present  in  an  experiment  of  this  diameter  so  complicates 
the  situation  thai  definite  conclusions  are  drawn  only  with  con- 
siderable difficulty.  Inorganic  salts  can  be  used  by  the  plant 
only  from  solution.  The  complexity  of  this  solution  increases 
with  the  number  of  ions,  which  must  be  rather  large  since  the 
plant  cannot  make  normal  growth  unless  certain  ions  are  present. 
To  further  complicate  the  situation,  all  the  salts  may  be  avail- 
able which  are  required  for  growth,  but  the  unbalanced  condition 
of  the  solution  may  cause  injury  to  the  growing  plant.34  This 
condition  of  balance,  in  turn,  seems  to  be  related  to  the  total 
concentration  of  the  solution  as  well  as  to  its  qualitative  compo- 
sition. ;'  In  this  connection  it  is  important  to  note  that  if  it 
were  possible  to  keep  the  balance  in  the  solution  constant  by 
renewal  of  salts,  growth  differences  would  be  less  marked  than 
when  the  plant  grows  in  a  solution  in  which  the  balance  is  con- 
stantly changing  due  to  absorption  of  ions  by  the  plant.38  All 
of  the  above  points  must  be  taken  into  consideration  in  any  ex- 
perimental work  which  is  done  in  this  field  of  investigation.  The 
exact  influence  which  the  concentration  of  the  solution  lias  upon 
the  complicated  physiological  processes  concerned  in  plant  nutri- 
tion is  a  problem  which  can  be  solved  only  by  the  gradual  ac- 
cumulation of  a  mass  of  evidence  bearing  upon  the  subject.  The 
complexity  of  the  whole  problem  is  such  as  to  require  more  than 


m  Loeb,  Archiv.  ges.  Physiol.,  vol.  88,  pp.  68-78,  1902,  and  Airier.  Jour. 
Physiol.,  vol.  ::.  pp.  327  338,  1900;  Osterhout,  Science,  a.  s..  vol.  35,  pp. 
L12    L15,  L912,  and  .lour.  Biol,  ('hem.,  vol.  1,  p.  363,  1906. 

35  <ii|,.,   toe.  cit. 

seBrenchley,  Ann.  Bot.,  vol.  30,  pp.  77  90,  1916. 


372        University  of  California  Publications  in  Agricultural  Sciences    [Vol.  1 

the  evidence  of  a  single  set  of  experiments  for  proof.  The  evi- 
dence presented  by  the  work  herein  reported  is  an  addition  to 
that  already  reported  by  other  investigators,  who  have  shown 
that  the  absorption  is  influenced  to  a  more  or  less  marked  degree 
by  the  concentration  of  the  solution.  Conclusions  which  have 
been  reached  in  regard  to  the  effect  of  certain  variables  in  this 
study  must  be  understood  to  apply  only  in  the  case  of  the  specific 
combinations  of  salts  studied,  and  in  connection  with  the  growth 
of  the  tobacco  plant  in  sand  cultures. 

The  experiments  herein  reported  have  in  part  been  made 
possible  by  that  portion  of  the  Adams  fund  allotment  of  the 
Department  of  Agriculture  of  the  University  of  California  placed 
at  the  disposal  of  Professor  W.  A.  Setchell  of  the  Department  of 
Botany.  It  is  a  pleasure  to  acknowledge  indebtedness  to  Pro- 
fessor Cbarles  B.  Lipman  and  to  Dr.  T.  H.  Goodspeed,  who  have 
by  helpful  advice  and  criticism  directed  the  work. 

SUMMARY 

Results  are  above  given  which  deal  with  the  influence  of  tin: 
composition  and  concentration  of  the  nutrient  solution  on  sixty 
different  plants  of  an  F4  species-hybrid  of  Nicotiana. 

1.  2000  g.  of  washed  sand  of  known  composition  was  used  as 
a  culture  medium  for  each  plant. 

2.  The  salts  used  were  NaN03,  Ca(H2P04)2,  K2S04,  and 
MgS04. 

3.  The  salts  were  so  distributed  as  to  give  at  least  three  im- 
portant variables :  first,  as  to  a  single  nutrient  salt ;  second,  as 
to  total  concentration  of  salts;  and  third,  as  to  the  balance  of 
salts  in  the  solution. 

4.  The  influence  of  the  solution  on  the  growth  of  the  plant 
was  judged  by  the  following  criteria :  height,  leaf  length,  leaf 
width,  flower  production,  dry  weight  of  tops. 

5.  Nitrogen  is  a  more  important  growth-limiting  factor  than 
phosphorus,  and  phosphorus  is,  in  turn,  more  important  in  this 
capacity  than  potassium. 

6.  The  total  concentration  of  the  solution  has  a  marked  in- 
fluence upon  growth.    Plants  growing  in  solutions  of  low  concen- 


L917         lyres:  Nutrient  Solution  on  Plants  Grown  in  Sand  Cultures         373 

tration  were  m  general  superior  to  those  grown  in  solutions  of 
higher  concenl  ra1  ion. 

7.  Flower  3  ield  as  well  as  vegetal  ive  vigor  is  influenced  by  t  he 
composition  and  concentration  of  the  outrient  solution. 

8.  The  physiological  balance  of  salts  in  the  solution  is  an  im- 
portaul    factor   which    must    be   taken    into  consideration    in   con 
nection  with  the  composition  and  concentration  of  the  solution. 
Growth  is  influenced  by  a  combination  of  all  of  these  factors. 

9.  A  quantitative  analysis  of  the  sand  used  in  each  pot  was 
made  after  the  plants  were  harvested. 

10.  Evidence  of  adsorption  is  seen  in  the  results  of  the  quan- 
titative analysis  of  the  water  extract  from  the  sand. 

11.  The  concentration  of  the  nutrient  solution  clearly  affects 
the  economical  use  of  nil  rogen. 

12.  High  ratios  of  potassium  added  to  potassium  remaining 
after  growth  usually  occur  where  the  <\yy  weight  production  is 
greatest. 

13.  Less  calcium  is  absorbed  from  solutions  of  low  total  con- 
i  entration  than  from  those  which  have  a  high  total  concentration. 

14.  Calcium  seems  to  be  used  with  greater  economy  in  solu- 
tions where  the  total  concentration  is  low  than  in  solutions  in 
which  the  total  concentration  is  high. 

/  ransmitted  April  .-/,  1916. 


PLATE 

5 

Treatment 

NaN03 
Grams 

Ca(H2P04)2 

Grams 

KoSO., 
Grams 

MgS04 
Grams 

Total 
Grams 

Pot 

ID] 

.02 

.3 

.6 

.24 

1.16 

Pot 

]D2 

2 

.3 

.6 

.24 

1.34 

Pot 

IDS 

1.0 

.3 

.6 

.24 

2.14 

Pot 

ID4 

2.0 

.3 

.6 

.24 

3.14 

Pot 

ID5 

3.0 

.3 

.6 

.24 

4.14 

•"■74 


_.  *l 


n 

> 


> 
a 

30 

CO 

n 


< 

o 


> 
-< 


> 


PLATE 

6 

Treatment 

NaNOa 
Grams 

Ca(H»P04)o 
Grams 

K2so4 

Grams 

MgS04 
Grams 

Total 
Grams 

Pot 

IA4 

2.0 

1.2 

2.4 

.96 

6.56 

Pot 

IB4 

2.0 

.8 

1.6 

.64 

5.04 

Pot 

IC4 

2.0 

.6 

1.2 

.48 

4.28 

Pot 

ID4 

2.0 

.3 

.0 

.24 

3.14 

[376] 


z 


o 


"0 

c 

03 


> 

o 
po 

CO 
O 


o 


PLATE 

7 

Treatment 

XnXO, 
Grams 

Ca(H2P04)o 
Grams 

KoSOj 
Grams 

MuS04 
Grams 

Total 
Grams 

Pot 

IC1 

.02 

.6 

1.2 

.48 

2.30 

Pot 

1D3 

1.0 

.3 

.6 

.24 

2.14 

Pot 

IB1 

.02 

.8 

1.6 

.04 

3.06 

Pot 

1D4 

2.0 

.3 

.6 

.24 

3.14 

|  37*  | 


« 


>l 


M 


co| 


o 


CO 


o 

en 
n 


< 
o 


"0 


• 


PLATE  8 

Treatment 

NaN03 
Grams 

Ca(HoPO,)2    KoS04 
Grams          Grams 

MgSOj 
Grains 

Total 
Grams 

Pot 

1IB1 

2.25 

.02           1.6 

.64 

4.51 

Pot 

IIB2 

2.25 

.1             1.6 

.64 

4.59 

Pot 

1IB3 

2.25 

.2             1.6 

.64 

4.69 

Pot 

IIB4 

2.25 

1.0             1.6 

.64 

5.49 

Pot 

IIB5 

2  12  5 

2.0             1.6 

.64 

6.49 

[380] 


o 
> 


~0 

03 


o 

'J, 


CO 

n 


o 


-■: 

IT 

LO 

l — i 

0 

I- 
>- 


Pl.ATE 

9 

Treatment 

NaNO., 
Grams 

Ca(H2P04)2 
Grams 

K2SO, 
Grams 

MgS04 
Grams 

Total 
Grams 

Pot 

EIA3 

3.00 

.2 

2.4 

.96 

6.56 

Pot 

IIB3 

2.25 

.2 

1.6 

.64 

4.69 

Pot 

IIC3 

1.5 

.2 

1.2 

.48 

3.38 

Pot 

IID3 

.75 

,2 

.6 

.24 

1.79 

[382] 


o 


c: 

03 


33 


CO 

n 


O 


PLATE   10 

Treatment 

NaNOs 
Grams 

Ca(HoPO,)=    KoSO, 
Grams          Grams 

MgS04 
Grams 

Total 
Grams 

Pot 

11C1 

1.5 

.02              1.2 

.48 

3.20 

Pot 

IIC3 

1.5 

.2             1.2 

.48 

3.38 

Pot 

IIB1 

2.25 

.02           1.6 

.64 

4.51 

Pot 

IIB4 

2.25 

1.0             1.6 

.64 

5.49 

[384] 


o 


c 

CD 


CD 

C/5 

n 


PLATE 

11 

Treatment 

NaN03 

Grams 

Ca(H2P04)s 
Grams 

K.SOj 
Grams 

MgSO, 
Grams 

Total 
Grams 

Pot   IB3 

1.00 

.8 

1.6 

.64 

4.04 

Pot   IIB3 

2.25 

2 

1.6 

.64 

4.69 

Pot  n  ib:; 

2.25 

.8 

2 

.64 

3.89 

'386  J 


/.   CALIF.    PUBL.  AGR.   SCI.   VOL. 


[AYRES] 


PLATE 

12 

Treatment 

NaKOs 
Grams 

Ca(H2PO.,),. 
Grams 

K2SO, 

Grams 

MgSO, 
Grams 

Total 
Grams 

Pot 

1IID1 

.75 

.3 

.02 

.24 

1.31 

Pot 

IIID2 

.75 

.3 

.1 

.24 

1.39 

Pot 

IIID3 

.75 

.3 

2 

.24 

1.49 

Pot 

IIID4 

.75 

.3 

1.0 

.24 

2.29 

Pot 

IIID5 

.75 

.3 

2.0 

.24 

3.29 

f:;ss] 


n 
> 


<Z 


CD 

n 


< 
o 


PLATE 

13 

Treatment 

NaN03 
Grams 

Ca(H2PO.,)2 
Grams 

KoS04 

Grams 

MgS04 
Grams 

Total 
Grams 

Pot 

IIA1 

3.00 

1.2 

.02 

.96 

5.18 

Pot 

IIIB1 

2.25 

.8 

.02 

.64 

3.71 

Pot 

IIIC1 

1.5 

.6 

.02 

.48 

2.60 

Pot 

IIID1 

.75 

.3 

.02 

.24 

1.31 

I  :;!>(i  I 


n 


"0 

c 

03 


> 

CI 

-p 

CO 
O 


< 

o 


> 

■< 


□ 

r" 


PLATE  14 

Treatment 

Plant  growing  in  washed  sand 
Plant  growing  in  soil 

NaN03     Ca(H2P04)2    KL.S04        MgSO.,  Total 

Grams  Grams         Grams         Grams  Grams 

Pot    EIIB2  2.25  .8  .1  .64  3.79 


[392] 


UNIV.   CALIF.   PUBL.  AGR.   SCI.   VOL.    I  [AYRES]    PLATE  14 


PLATE 

15 

Treatment 

NaNO:! 
Grams 

Ca(H2P04)2 
Grams 

K,SO, 
Grams 

MgSO, 
Grams 

Total 
Grams 

Pot 

ID2 

.2 

.3 

.6 

.24 

1.34 

Pot 

IID2 

.75 

.1 

.6 

.24 

1.69 

Pot 

IIID2 

.75 

.3 

.1 

.24 

1.39 

[394] 


UNIV.   CALIF.    PUBL.   AGR.   SCI.    VOL.    I 


[AYRES]   PLA1 


